The use of the Internet worldwide is ever increasing with a high growth rate in the developing countries around the world. However, many emerging business centers in regions near the Equator are handicapped by poor connectivity to the Internet. These centers are typically located in countries with limited national high bandwidth network infrastructure, and sometimes surrounded by rugged terrain that makes terrestrial and undersea cable connections impractical.
Nevertheless, there is a continuing demand for high bandwidth connectivity to the Internet in these countries. Many of the most rapidly growing markets are both near the Equator and poorly connected via undersea cables. For some of the larger countries, the internal network infrastructure is relatively primitive. Furthermore, natural disasters can also disrupt connections, and the ability to rapidly reconfigure a communication network to reconnect the affected areas can be extremely valuable. In addition to the underserved markets, the major global telecom carriers of significant and growing wholesale bandwidth have needs for backup and replacement bandwidth to maintain Quality of Service agreements.
Geostationary Earth Orbit (GEO) communication satellites have inherently high latency, while other satellite communication networks suffer from some combination of limited worldwide connectivity, low bandwidth, or cost. The GEO satellites offer coverage of a reasonably large fraction of the Earth per satellite but have long communication paths, resulting in a signal latency of at least 120 msec per path. Moreover, multiple bounces may be required to provide routing, and connection between ground sites not within footprint of same satellite may require ground connections.
Recently, a constellation of Medium Earth Orbit (MEO) satellites have been designed to satisfy the need for an optical relay on a space platform that is capable of linking a redundantly connected ring of MEO satellites to a network of ground sites. This constellation of MEO satellites can do so transparently and independent of the optical format and modulation scheme. The communications relay payload on each satellite is configured to support growth of the constellation by being able to rapidly reconfigure the network to drop any failed satellite out of the network. However, these optical communications relay payload and architecture are optimized for transmitting large amounts of data from one ground site (Lightway) to another Lightway through space, but do not have any ability to uplink data from a Lightway to a satellite or to downlink data from a satellite to the Lightway. The present invention enables the laser relay satellites (LRSs) to communicate with other satellites, through both laser and electrical (e.g., RF) links, when desired.